Something doesn't feel & sound right...

[barishiman]

Addo:

I did the adjustmentby your specs. At first it looked backwards as I started to adjust the valves. I then pulled out my Chilton's manual and it said to start on TDC as the compression stroke ends. After that it looked fine. I adjusted the valves per your order. Here is the new compression readings on a cold engine:

1.) 170
2.) 0
3.) 0
4.) 150
5.) 170
6.) 30

Ok, can anyone exlpain the oddity of this to me! Yesterday I had compression on all cylinders. Now I've got 2,3 with none and 6 trying to give me a reading. I re-adjusted the valves again and got the same results. So then I did a wet test and still the same results. Something is very wrong and I'm about to go nuts. I have no unearthly idea what is happening. I didn't even attempt to start the car as the compression readings weren't promising at all. I"m going to grab some lunch and watch a movie. Maybe tonight I'll go work on the car again. So what should I do? make the valves on 2,3, & 6 loose and try a compression reading again?

And yes I have little patience when I'm been at this for two weeks.

Andrew

 

[Anonymous]

Is this a mechanical cam or hydrolic

 

[rbohm]

8) i think we have it narrowed down to the valves being way too tight. start by getting the engine to #1 cylinder on the compression stroke. that gets the first valves on the cam base circle. then tighten the rokers untill you have no vertical movement of the pushrod, much easier then no rotational movement. then 1/4 turn more on the adjusting screw. repeat this on each cylinder in turn. DONT use the order in the book it will only confuse you. if the two cylinders that were low are still low, then you will need to pull the head.

 

[barishiman]

I assume its an hydrolic cam: hydrolic lifters and adjustable rockers.

rbohm:

I'll go ahead and set cylinder #1 on the compression stroke. I'll back off each valve again and try it all over again. Before this morning, every push rod was able to move in a rotational movement when there was no pressure on the valve. So I guess again the valves are too tight. I'll be back in a few with the compression ratings again.

Andrew

 

[barishiman]

rbohm:

I did it your way and I'm back to where I started:

1.) 160
2.) 160
3.) 90
4.) 150
5.) 170
6.) 80

I did remember one thing that I haven't mentioned yet, if it means anything at all. When I had the engine warm and did a wet test on 3, there were puffs of white smoke coming from 2 out of the spark plug hole. I"m planning to take off the head in a couple of days, maybe tonite if I can get my brother.

Andrew

 

[rbohm]

8) at this point then i would either blown head gasket or bad valves, and with the revelation of the white smoke, i would say head gasket. the head has to come off either way.

 

[barishiman]

Thanks rbohm. I too think my head gasket it blown in some way. To me, it feels that the head bolts are bottoming out. I'll run out and get another head gasket, washers, and try to find some taps in the tool chest. Looks like I'll have to pull the head myself.

Andrew

 

[barishiman]

Ok chaps, took the head off and here's the updates (no pics, but maybe later tonite).

head gasket is intact and looks brand new (it was brand new anyways)

1,2,4,5, pistons are black while 3 & 6 look fairly clean. Found a piece of metal 1.5cm long ontop of piston 2.

As for the head, 1&2 are black, 4 & 5 are pitch black, and 3& 6 are little black.

Adam, I went ahead and followed your "back to basics" check list:

chase the threads: yes, got some crap out
check thread depth: all look fairly the same
lay a straightedge on the deck: straight both N-S and diagnol
check balancer marks: ok
inspect bores and measure size: the bores looked good, I compared them to my Chilton diagram. As for the size I didn't check that (don't have the tool for that laying around yet).
check valve operation: I will try to do that tonight or tomorrow and inspect the valves. The valve tips don't look damaged when I looked at the head.
dial the cam: ? I don't know what that is....
Stage the torquing: will do that again

So I'm ruling out the head gasket and either I have bad valves or something is wrong with the pistons/piston rings.

What do ya'll think?

 

[rbohm]

8) since the wet and dry tests were about the same, i say valves.

 

[Anonymous]

Could it be as simple as just re-lapping the valves? Or is it likely that something is bent?

And the 1.5cm piece of metal in #2 is scary. Did it look like a piece of broken ring, or a shaving of some sort? Are the threads in the #2 spark plug hole intact?

--mikey

 

[barishiman]

I took my head to the machine shop today for inspection of the valves. The guy said he'll look at the valves and if their ok he'll won't charge me anything. As for that piece of metal I found, it was from a hela-coil (spl?) we installed on one of the exhaust lobes where the threads were about gone. I guess it got stuck in the valve and when it opend the piece of metal fell out. I hope to hear from the machinest after the weekend is over. Once I get my head back, I plan to run the car and check the compression. If I still have bad compression, looks like I'll have to tear out the pistons which I don't want to do. Ah, the fun of making a performance six! Loving it!

 

[BIGREDRASA]

As long as the head is off, I would do an in-frame rering and rebearing job. At least do rings and rod bearings. You will at least have new rings, and you may find your problem. You have nothing to lose by throwing in the new rings and rod bearings. What the hey, as long as you drop the pan, throw in a new oil pump.

 

[addo]

That might be ideal, but our friend wants to get back and running. Right now, a successful procedure is the principal objective, hopefully not more work. As I mentioned, inspecting the bore size and condition is the key to knowing the residual motor life.

Andrew, a simple set of Vernier calipers will tell you the bored diameter. The amount of "lip" below that (about 1/4") is the bore wear. Diagonal-like marks on the cylinder walls are from the honing stone. If you can see them, there's life in it yet. If the "lip" is more than a few thou (can it hook your nails?), the motor is getting close to rebore time. But if the bore is out to the max already, then it is getting close to block life.

My basic test of valve operation is to be able to depress them with the palm of my hand and feel/hear the buggers "snap" back into their seat. With HD springs, this is hard on your paws.

Dialling the cam requires a dial gauge and magnetic stand, as well as a degree wheel. There are a few illustated tutorials on the net; maybe someone can list a URL. At least satisfy yourself it isn't opening way out of whack. Pulling the balancer and timing cover is one way (checking the dots are collinear with the shaft centres). But do this and you'll need to replace the gasket and oil seal almost certainly. The side-to-side slop in the chain (one side pulled taut) is supposed to be less than 1/2".

Hope this helps!

Adam.

 

[barishiman]

Unfortunately I already put in a new oil pump and put a new gasket on for the oil pan. That was enough trouble. Like Adam said, I'm trying to get this running without more work to do. I took a look at the piston walls and I can clearly see the diagnol - like marks from the honing stone. Would the "lip" be at the top? There is a dark area at the top of each piston wall about 1/4". Some feel rough and others smooth. The PO had the engine rebuilt at a high school for a project car. My guess is he went with a stock cam and .030 oversized pistons. I don't know the max bore for my block (66 block). I feel that I can go up some on the piston size, but I"m planning on doing that unless it has to come down to it.

 

[BIGREDRASA]

Sounds like you don't have that much wear, then. Hope the problem was all in your head. I mean, the car's head.

 

[addo]

I was just trying to speak from experience. Otherwise you end up dismantling everything down to the molecular level almost, before restoring it and reassembling. It's not the way most want to go.

 

[Falcon62]

Andrew - clean the top of a piston off with a wire brush and you should see a number, something like 020, 030, etc, stamped on it. This will tell you the amount of overbore. Ideally, the block should not be overbored more than .030", but they can be taken further. I know several of us have gone beyond that, myself included, but it wasn't what I wanted.

The dark area near the top of the bore is where you would find the lip or ridge. If you have a ridge, or lip, what you are feeling is the difference between the machined bore finish and the wear created by the piston rings. Try to clean off any carbon build-up before determining whether you can catch your fingernail on it. Generally speaking, if there is a discernable ridge, then you've got some wear. A dial caliper (better than a vernier caliper for older eyes like mine) will work to meaure the bore at the very top, but if you want to know how much wear there is below the ridge you're going to need an inside micrometer. A dial bore gauge is best, but hard to use with pistons in the bore.

As for cam timing, you didn't replace the timing chain and gears did you? I can't remember what your pre-modification state was, good running engine, poor runner, not running, etc. If you had a good running engine before, and haven't messed with the timing chain and gears, your cam timing has to be ok. That would leave only top side stuff like valves and ignition timing as likely culprits.

 

[barishiman]

When I cleaned the engine down, I found this on top of the piston: .030. Percondition of the engine was that it ran great. Had the stock dizzy, Autolite 1100 (ponycarb), new dizzy cap, wires. That about did it. We just wanted to get the car on the road and it ran beautifully up to the point the carb litterally blew up on the inside. Thus I came across FSP and started the mod for performance. I never touched the timing chain, cam, piston, or anything else on the underside of the engine. All I did was replace the oil pump and put in a new oil pan gasket. The oil gasket needed to be replace as the whole right side was leaking along the seem. The machinest I went to did the valve job. I had him put in 1.75 intake valves, 3 angle valve job, re-surface the bottom. I ported and polished the exhaust with my dremel.

But like I said, the car ran great before the carb went out. The PO had it for his son for high school. Then we bought it for me to drive to high school and then to college. College was the ultimate test for the car. I had a good 60 miles a day to drive. The car held out and did an amazing job. So I'm hoping that my problem is either with the valves or the head bolts giving false torque readings. I've got some head bolt washers ready when I get the head back sometime next week. This time I won't preload the valves so excessively like I did before.

 

[Anonymous]

I have a 68 with a 200 and C4. All of a sudden the idle was all screwed up and the car would die when in gear. When cold started it felt like the engine was going to come out fromunder the hood it was so rough. I checked everything and was stumped till I talked to my dad who used to rebuild Mustangs back in the lat 70s early 80's. Told me to check the vacuum line that goes to the tranny. Well, the hose was completely deteriorated. I replaced it, fired her up and with a small re-adjustment of the timing I was back to a nice even idle.

 

[barishiman]

Just got off the phone with my machinest. He says that I had two bad exhaust valves but he didn't give me any details. He also said something about some kind of wear near the rocker arms shafts. He wasn't too clear on that either, but he'll fix everything for free except for the two bad exhaust valves. Hopefully by the end of the week it'll be done.